Roller skates have been used for many decades. Originally roller skates consisted of a boot attached to front and back pairs of wheels. Such roller skates were popular as a leisure activity, but because of the wheel arrangement and attendant limitations on the speed and stability of the skater, they were not suitable as a mode of transportation.
More recently in-line skates have become popular. In-line skates typically have four or five wheels mounted in a common plane in spaced-apart alignment. This allows for greater speed.
The turning radius of the in-line skate is dependent upon a number of factors, one of which is the length as measured from the axle of the front wheel to the axle of the back wheel, known as the wheelbase. A longer wheelbase is advantageous for stability and speed when skating straight, and often the wheel frame is designed so that front wheel extends beyond the toe of the boot and/or the rear wheel extends beyond the heel of the boot, which increases the length of the supporting wheel assembly and thus improves stability. But because the wheel base is fixed and the wheels are in line, basic geometry dictates a certain minimum turning radius for a wheelbase of any specific length. In order to effect a tight turn, a skilled skater will slow down and lift one leg over the other (known as a “crossover”), during which the skater's stability is reduced; even doing so, the wheelbase of the supporting skate still limits the radius of the turn.
It would accordingly be advantageous to provide an in-line skate that has a long wheelbase for stability during straight runs, but is capable of achieving a turning radius that is shorter than that dictated by the geometry of the long wheelbase.